1. Field of the Invention
The present invention relates to a needle electrode serving as a corona current generator in an electrical appliance, such as, an oven. More particularly, this invention relates to a shield device for safely storing the needle electrode out of reach by the operator when the needle electrode in the appliance is not in electrical use. The present application is particularly adapted for use in connection with a needle electrode arrangement, such as is disclosed in my copending application entitled Enhanced Heat and Mass Transfer Apparatus, U.S. Ser. No. 488,556, filed Apr. 25, 1983 and having the same assignee. To the extent appropriate to the present invention, the disclosure of the above-identified copending application is incorporated herein by reference.
2. Description of the Prior Art
In the above-identified copending application there are disclosed two needle electrodes embodied in an oven appliance. The two electrodes operate in conjunction with food at high potential in the oven for generating controlled corona current which is applied to surfaces of the food in order to maximize heat and mass transfer so as to minimize cooking time.
While the disclosed apparatus for enhancing heat and mass transfer successfully operates to substantially reduce the cooking time of food, the apparatus and particularly the disclosed needle electrode arrangement used in an appliance poses problems. For example, the upper needle electrode comprises an array of necessarily sharp-pointed needle members that project downwardly towards the food in the oven. The needles are thus exposed in the chamber to present a potential source of injury to the operator's hands when exchanging food in the oven and when attempting to clean the oven walls. Another problem relating to the exposed needles is that they may receive a damaging blow that may bend or even break the needles which may reduce the operating effectiveness of the electrode. A further problem concerns the array of needle members presenting an oven surface which is most difficult to clean and may be regarded as aesthetically not attractive to the operator. Accordingly, there is a need for enabling the use of a needle electrode in an oven appliance yet avoiding the problems presented by the exposed appearance of the needle members when the electrode is electrically inactive.